Wire



Patented Mar. 9, 1943 OFFICE B. Rinck, La Grange, and James W. Downers Grove, m, assignors to Western Electric Qompany, Incorporated, New York, N. E, a corporation or New York No Drawing.

Application May 23, 1940,

Serial No. 336,764.

Claims. (Ci. Flt-4.34)

and coldrdrawing the rod into wire of the desired This invention relates to wire, and more particularly to the composition and manufacture of wire for use in overhead telephone transmission lines- Wire employed in telephone circuits must have satisfactory electrical properties primarily, and its physical properties are subservient to the electrical requirements. However, in many instances the physical characteristics of the wire are also important because they usually determine the manufacturing methods that can be used as well as the nature of the installation in which the wire can be employed. For example. in overhead telephone transmission lines the tensile strength and ductility of the wire largely establish and limit the permissible spacing of the poles and related supporting structure, such as cross-arms, insulators and guy wires. Consequently, high strength values are often desirable and in many cases the cost of the installation can be reduced by an improvement in wire strength, provided that the electrical properties of the wire are maintained at satisfactory values. Steel wire has been used for overhead telephone lines in some locations. This wire contains the usual carbon manganese, silicon, sulphur and phosphorus, and it has been possible to vary the proportions of these ingredients to some extent to influence the properties of the wire. However, these possibilities are limited because in general the composition changes which increase the strength of the wire also detract from its electrical properties and, consequently, any improvement in physical properties is usually accompanied by a deterioration in the service performance of the telephone line.

size.

In its preferred form the alloy has the following essential composition:

Per cent Minimum Optimum Maximum 38 45 02 g: O0 er-.- 2O M n ganosn :40 Iron+impuritics Balance Phosphorus .07 Silicon .02 Sulfihlll' .05

In one satisfactory procedure for compounding a ferrous alloy of the above composition, steel scrap, pig iron and iron ore are first melted to- An object of this invention is the provision of an improved telephone transmission wire having high tensile strength, high ductility and low electrical resistivity and which is suitable for use in overhead lines.

In accordance with one embodiment of the invention, a telephone transmission wire with improved electrical and physical properties is provided by compounding an alloy comprising essentially iron, carbon, vanadium, copper and manganese with a controlled maximum content of phosphorus, silicon and sulphur, rolling the alloy into a rod at a high. finishing temperature,

the final rolling pass.

gether in a suitable furnace. Vanadium, in the form of ferro-vanadium, is then added to the melt and in cases where the manganese content is deficient, form-manganese is also added. The carbon content of the alloy is controlled by a. suitable degree of oxidation during melting or by addition of a suitable carbonaceous material, such as coke or a high purity pig iron, just prior to pouring.

The completed alloy is cast into ingots and the ingots are hot rolled into cylindrical rods. The finished rod diameter is based upon the final wire size desired and in general, the rod diameter should be about twice the wire diameter. Prior to the rolling operation, the ingot is heated to a temperature around 2,100 F., and the rolling is then completed rapidly to minimize cooling of the alloy during the rolling process. The temperature of the alloy is held within a restricted range throughout the rolling operation and the temperature of the alloy is at least 1,800 E, in

The completed rod is permitted to cool in air at room temperature.

The rods are cold-drawn into wire of the desired size, such as a .105" diameter wire which is used commonly for telephone lines. For .105" wire, a rod about .210" in diameter is employed.

Preparatory to drawing, the rods are pickled in acid, such as sulphuricacid, then sprayed with water to promote a fine surface rust formation which carries the drawing lubricant,-and finally coated with a lubricant, such as soap. With the above composition and rolling practice, the rod can be cold-drawn into wire in a single operation incorporating a series of dies with progressively smaller apertures without any intermediate annealing.

The wire may then be galvanized by any conventional method, such as an electro-deposition or a hot dip process, which increases its diameter to about .109". The wire is then readyfor use.

The .105" diameter wire weighs about 154 pounds per mile before galvanizing and about 162 pounds per mile after galvanizing. This particular wire size has a tensile strength in excess of 1400 pounds, or more than eight and one-half times its weight per mile. The corresponding minimum tensile strength of substantially 150,000 pounds per square inch is exhibited proportionally in wires of other sizes. The elongation of the wire, measured on a ten inch length, is greater than 7%. l

The .109" diameter wire has a D. C. resistance of 36 ohms per mile. Its P, M. 0. or pound-mileonm. rating (D. C. res. per mile X weight per mile) is thus less than 5,900 and this low maximum value is maintained in conductors of various diameter and cross-sectional areas. The electrical and magnetic characteristics of the wire enable it to transmit currents within the voice frequency range, such as are employed in telephone circuits, over a considerable distance without distortion or excessive line losses.

The combination of improved properties possessed by this wire facilitate its economical use in overhead telephone transmission lines. The electrical and magnetic properties of the conductor insure satisfactory current transmission between telephone stations. The high strength .of the wire permits the telephone poles and associated equipment, such as cross-arms, braces, insulators and stay wires, to be spaced widely apart to minimize the cost of the supporting structure. Substantial tensile strength coupled with high ductility enable the wire to withstand sudden and severe stress applications due to wind action, sleet accumulations, and other causes with the result that the necessity for repairs, and the attendant service interruptions, are infrequent.

Although the use of this product as overhead telephone line wire has been described specifically, it will be apparent thatit can be used advantageously for other purposes. Also, it is feasible to make some modification in the specific composition and manufacturing processes above described, and it is to be understood that the invention is limited only by the scope of the appended claims.

What is claimed is:

1. A telephone transmission line comprising a current carrying conductor containing from .30% to .45% carbon, from .02% to 04% vanadium, from .20% to .35% copper, from 35% to 45% manganese, and the balance iron plus impurities, said conductor having a sufllciently high electrical conductivity so that the product of its direct current resistance per mile in ohms'and its weight per mile in pounds is less than 5900.

2. An overhead telephone transmission line comprising a current carrying conductor containing from .30 to .45% carbon, from .02% to .04% vanadium, from .20% to 35% copper, from .35% to .45% manganese, from 0%. to .07% phosphorus, from 0% to .02% silicon, from 0% to .05% sulphur, and the balance iron, said conductor having a sufficiently high electrical conductivity so that the product of its direct current resistance per mile in ohms and its weight per mile in pounds is less than 5900.

3. In an overhead telephone transmission line, a current carrying conductor comprising substantially .38% carbon, .03% vanadium, .25% copper, .40% manganese, and the balance substantially iron, said conductor having a sufllciently high electrical conductivity so that the product of its direct current resistance per mile in ohms and its weight per mile in pounds is less than 5900.

4. A telephone transmission line, a, current carrying conductor comprising .38% carbon, .03% vanadium, .25% copper, .40% manganese, .07% phosphorus maximum, .02% silicon maximum, .05% sulphur maximum and the balance iron, said conductor having a sufficiently high electrical conductivity so that the product of its direct current resistance per mile in ohms and its weight per mile in pounds is less than 5900.

5. An overhead telephone transmission line comprising an alloy wire for transmitting telephone currents within the voice frequency range, said alloy containing iron, carbon, vanadium, copper and manganese, and said wire having a tensile strength in excess of eight times its weight per mile and a sufllciently high electrical conductivity so that the product of its direct current resistance per mile in ohms and its weight per mile in pounds is less than 5900.

FRANKLIN B. RINCK. JAMES W. SCOTT. 

